The present invention relates to an assembling device for assembling and disassembling a fuel injector, for example a high-pressure direct injector, into and from a mounting hole in a cylinder head of an internal combustion engine. Fuel is injected directly into the combustion chamber of the internal combustion engine through this high-pressure direct injector.
An assembling device having a jacket body at least partially surrounding the fuel injector is described in German Patent Application No. 197 05 990. A collar section directed inward is formed at a first end of the jacket body, and a collar section directed outward is formed at a second end of the jacket body, opposite the first end. While the collar section directed radially inward can be inserted into a groove of the fuel injection valve, she collar section directed outward protrudes outward from the mounting hole of the fuel injection valve. An appropriate tool, for example, an assembling iron, can engage in the collar section protruding from the mounting hole of the cylinder head in order to lift the assembling device together with the fuel injection valve from the mounting hole. In some cases considerable disassembling forces are required because the fuel injection valves of the fuel injectors may seize in their mounting holes. Therefore the cylinder head, which may be made of light metal, for example, may be disadvantageously damaged by the mounting iron or other lifting tools. Which is disadvantageous. Furthermore, it is a disadvantage in the case of the conventional assembling device that the mounting device transmits no hold-down force to the fuel injector during the operation of the internal combustion engine, but the fuel injector and the assembling device are held in the mounting hole disadvantageously by friction forces alone.
U.S. Pat. No. 4,561,159 describes a disassembling device for a diesel injector. An end area of the fuel injector opposite the spray orifice can be inserted at the side into a slit in the disassembling device. The disassembling device is not inserted into the mounting bore of the cylinder head and it does not remain in the mounting bore when assembled. The disassembling device described in U.S. Pat. No. 4,561,159 is instead a tool extension which is attached to the fuel injector before disassembling the fuel injector. No hold-down force is transmitted to the fuel injector. Connecting the disassembling device to the fuel injector is a relatively complicated process.
The assembling device according to the present invention has the advantage over the conventional device that the at least one disassembling screw engaging in a thread of the collar section allows simple and damage-free disassembling of the fuel injector inserted into the assembling device. Disassembling takes place so that the assembling device with the fuel injector is continuously extracted from the mounting hole by tightening the at least one disassembling screw or advantageously plurality of disassembling screws.
The threads, each assigned to a disassembling screw, peripherally distributed on the collar section, for example two threads for two disassembling screws, can ensure that the disassembling force resulting from the tightening of the plurality of disassembling screws is directed axially, so that increased friction lock due to a radial force component is avoided. A symmetric, continuous pulling force is achieved through the simultaneous tightening of the disassembling screws. As an alternative, disassembling can also be performed by tightening the plurality of disassembling screws alternately.
It is particularly advantageous that openings, for example in the form of bore holes, are provided on the collar section, through which assembling screws engage a thread of the cylinder head. By tightening these assembling screws, sufficient hold-down force is transmitted to the assembling device and thus to the fuel injector to hold down the fuel injector against the combustion pressure prevailing in the combustion chamber during the operation of the internal combustion engine. The threads and the openings in the collar section are dimensioned, for example so that the assembling screws can be used as disassembling screws at the same time. For this purpose, the threads in the cylinder head and the collar section of the assembling device must have the same diameter and the same taper, and the openings must be dimensioned so that the corresponding screw diameters pass through them. When the fuel injector is disassembled, the mounting screws are loosened first and then the mounting screws used as disassembling screws are introduced in the thread of the collar section and tightened, whereby the assembling device with the fuel injector is extracted of the mounting hole in the cylinder head. No special disassembling screws need to be provided.
For example at least three openings spaced at an angular distance of 90xc2x0, are provided for the mounting screws. This ensures that the hold-down force on the assembling device and thus on the fuel injector is applied uniformly over the periphery.
According to a advantageous embodiment, the contact section of the assembling device engaging the fuel injector has an extension directed radially inward and an axial extension extending axially beyond the radial extension. The axial extension is used for transmitting the hold-down force to the fuel injector, while the radial extension engages a groove of the fuel injector to transmit the disassembling force to the fuel injector. The functions of hold-down and disassembling are separated on the contact section of the assembling device engaging the fuel injector. This has the advantage that the area of the disassembling groove of the fuel injector can be implemented by an injected plastic piece, and the area of the fuel injector engaged by the axial extension must be made of metal. This results in simple and cost-effective manufacturing of the fuel injector housing.
The assembling device can be economically manufactured by deep drawing from sheet metal.